I thought from what I read about The Buried Giant that it was a historical novel set in the days after the Romans left Britain. But it is really a fable or a fantasy novel or both.
Axl and his wife Beatrice are an old British couple who decide to go on a journey. They have recently become aware that their memories of the past are poor, as are everyone’s, but they vaguely remember they have a son. Years ago, their son moved to another village, and Beatrice has been wanting to visit him. Finally, they decide to go.
Beatrice has difficulty remembering the way to their first stop, a Saxon village she has visited before, but they find it by evening. The village is disturbed and possibly dangerous for the visiting Britons. A boy was taken by an ogre, but a strange warrior has brought him back. The villagers have seen a bite on the boy and want to kill him. But the warrior saves the boy, named Edwin. Once Axl and Beatrice leave the village the next day, they find themselves traveling with Edwin and the warrior Wistan.
This novel features ogres, pixies, treacherous monks, a British lord on the lookout for the Saxon warrior, an Arthurian knight, and finally a dragon whose breath has made everyone forget the past. It is about reconciliation, memory, aging, and death. As a fable, it doesn’t really characterize its protagonists; they are more like symbols. As such I wasn’t really compelled by the story.
In addition, a history class I have been taking recently indicates that it is unlikely any Britons would have been mixing freely with Saxons at this time. By the time the Anglos and Saxons began settling England in earnest, all the Britons had been pushed off to far western England and Cornwall. Although this novel does not really mention which part of England they are in, I understand that Britons did not tend to mix with the Angles and Saxons.